Intermediates for the preparation of dideoxycarbocyclic nucleosides

ABSTRACT

A therapeutic method is provided, employing an antiviral compound of the general formula: ##STR1## wherein Z is H, OR&#39; or N(R)  2 , wherein R&#39; is H, (C 1  -C 4 )alkyl, aryl, CHO, (C 1  -C 16 )alkanoyl or O═P(OH)  2 , Y is CH or N, and X is selected from the group consisting of H, N(R)  2 , SR, OR&#39; or halogen, wherein R is H, lower (C 1  -C 4 )alkyl, aryl or mixtures thereof, and the pharmaceutically acceptable salts thereof.

GRANT INFORMATION

This invention was made with Government support under Grant No. 5 R 01CA23263, awarded by the National Institutes of Health. The Governmenthas certain rights in this invention.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 623,348, filed Dec. 7, 1990,now pending, which is a continuation-in-part of U.S. patent applicationSer. No. 495,341, filed Mar. 19, 1990 now abandoned, which is adivisional of U.S. patent application Ser. No. 278,652 (filed Dec. 5,1988) (U.S. Pat. No. 4,931,559) which is a continuation-in-part of U.S.patent application Ser. No. 146,252, filed Jan. 20, 1988 (U.S. Pat. No.4,916,224).

FIELD OF THE INVENTION

The present invention relates to a therapeutic method employingdideoxycarbocyclic nucleosides which exhibit antiviral activity.

BACKGROUND OF THE INVENTION

Despite intensive effort to discover drugs that may be of value in thesystemic treatment of human immuno-deficiency virus (HIV) infections,such infections have been singularly resistant to chemotherapy. Theintracellular and intimate relation to nuclear metabolism of virusreproduction makes it difficult to destroy a virus without irreparabledamage to the host cell.

The discovery of the antiviral activity of vidarabine(9-β-D-arabinofuranosyladenine monohydrate) has led to the preparationof a large number of synthetic nucleosides. To date, only one syntheticnucleoside, 3'-azido-3'-deoxythymidine has been approved for treatingcertain AIDS patients, but it is a palliative, not a cure. ##STR2##

Although AZT is specifically active against retroviruses, its use hasled to side effects, including anemia, headache, confusion, anxiety,nausea and insomnia. The nucleoside analog, 2',3'-dideoxycytidine (DDC),exhibits an in vitro TI₅₀ of ca. 300 against HIV and may exhibit fewerside effects than AZT, but may also be eliminated more rapidly from thebody. ##STR3## The synthesis of adenine ("6-amino-purine") nucleosideanalogs in which the pentose sugar has been replaced withtris(hydroxy)-substituted cyclopentyl residues has yielded compoundswith substantial cytotoxic and antiviral activity. For example, thecarbocyclic analog of vidarabine, cyclaridine, is highly active againstHSV-2, but exhibits a low therapeutic index (TI₅₀ =10) against HIV invitro. Likewise, the carbocyclic analog of AZT is inactive against HIV.Therefore, it is clear that the structure-activity relationships betweenthe variously substituted carbocyclic nucleosides which have beenprepared and tested remain ill-defined.

Thus, a substantial need exists for chemotherapeutic agents effective toprotect mammalian cells against infection by viruses such as HSV-2, HIV,varicella-zoster, vaccinia, human cytomegalovirus (HCMV) and the like.

SUMMARY OF THE INVENTION

The present invention is directed tohydroxymethylcyclopentenyl-substituted purines and 8-aza-purines of theformula (I): ##STR4## wherein Z is H, OR' or N(R)₂, Y is CH or N, and Xis selected from the group consisting of H, N(R)₂, SR, OR' and halogen,wherein R is H, lower(C₁ -C₄)alkyl, aryl or mixtures thereof, wherein R'is H, (C₁ -C₄)alkyl, aryl, CHO, (C₁ -C₁₆)alkanoyl, or O=P(OH)₂, and thepharmaceutically acceptable salts thereof. Preferably, X is Cl, OR',most preferably OH; or N(R)₂, Y is CH, R is phenyl or H, and R' is H oracetyl. As used herein, the term "aryl" includes substituted andunsubstituted aralkyl (preferably ar(C₁ -C₄)alkyl) moieties. Preferredaryl moieties include phenyl, tolyl, xylyl, anisyl, or phen(C₁-C₄)alkyl, e.g., benzyl or phenethyl. Certain of these compounds areeffective antiviral and/or cytotoxic agents or are intermediates usefulfor the preparation thereof.

A given compound within the scope of the formula has two opticallyactive centers, indicated by the symbol (*) in formula I, either ofwhich can exhibit R, S or RS stereochemistry. Therefore, singleresolved, optically active enantiomers and diasteriomers of the presentcompounds are preferred embodiments of the present invention, althoughpartially resolved and racemic (±) mixtures are also within the scope ofthe invention. The four stereoisomers of the compound of formula I aredepicted below: ##STR5## wherein X, Y, Z and R' are defined hereinabove.The stereoconfigurations are given using thecyclopent-2-en-4-yl-1-carbinol nomenclature.

Certain of the compounds of formula I may exist as a mixture oftautomeric forms and all such tautomers are included within the scope ofthe invention.

A preferred compound of the invention is the optically active enantiomerof the formula II: ##STR6## wherein X, Y, Z and R' defined above and thestereochemistry at the optically active centers is as depicted. A wedgedline indicates a bond extending above the plane of the cyclopentenylring, while a dashed line indicates a bond extending below the plane ofthe cyclopentenyl ring.

Although generally compounds of formula I are not active against HSV-1,it is expected that some of them will exhibit specific antiviralactivity against other viruses such as hepatitis, HSV-2, EBV, RSV, PRV,HCMV and/or HIV, as well as against other retroviruses, such as thosebelieved to cause T-cell leukemia. Specifically, the racemic compound offormula I, wherein X is OH, Z is NH₂, Y is CH and R' is H (14a),strongly inhibits HIV infectivity in vitro. The TI₅₀ of this compoundvaried with the infected cell line which was used to assay for anti-HIVactivity, but generally fell between 200-400, and was determined to beas high as 667 in one assay. The acetate ester (R'=Ac) of 14a was alsoactive against HIV, giving 28% inhibition at 6 μg/ml. Compound 14a isalso active against HSV-1.

The fully resolved compound of formula II, wherein X is OH, Z is NH₂, Yis CH and R' is H ((-)14a) is also highly active against HIV[(1'R,4'S)-2-amino-1,9-dihydro-9-[4'-hydroxymethyl-2'-cyclopenten-1-yl[-6H-purin-one,or (1S,4R)-4-(2-amino-6-hydroxy-9H-purin-9-yl)-2-cyclopentenylcarbinol].Compounds of formula I wherein X is Cl or N(R)₂, Y is CH, Z is NH₂ andR' is H (13a and 15a, respectively) are also active against HIV, as arecompounds wherein X is Cl, NHz or SH, Y is CH, Z is H and R' is H (7a,9a and 10a, respectively). Compounds 7a, 9a and 10a, as well ascompounds of the formula I wherein Y═N, Z═NH₂, X═Cl, NH₂ or OH and R' isH (16a, 18a and 17a), are cytotoxic to cultured P-388 leukemia cells. Itis believed that the antiviral activity is due to an inhibitory effecton the ability of viruses to infect normal mammalian cells. The presentinvention is also directed to the intermediate compound of the formula(III): ##STR7## wherein Z is H or NH₂, Z' is H or NH₂, and X is halogen,preferably Cl, which is useful for the preparation of the purines of theinvention. Preferably, Z is NH₂, and Z' is H or both Z and Z' are NH₂.However, the compounds where Z═Cl, Z═NH₂ and Z'═H or NH₂ are not activeagainst HIV.

The (3-hydroxymethylcyclopentenyl)pyrimidine analog, 20a, is also withinthe scope of the present invention. Its synthesis from cyclopentene 2ais outlined in Scheme I, below. ##STR8##

In compounds 19a and 20a, R can be CH₃ or H. Thus, it is expected thatcertain of the compounds of the present invention will be useful againstviral infections or virus-associated tumors, and the method of their useto inhibit viral infectivity or tumor growth in vitro or in vivo is alsowithin the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram summarizing the synthesis of the purines of thepresent invention.

FIG. 2 is a graphic depiction of cells exposed to 14a/control cells (%)plotted vs. concentration of 14a for both uninfected cells and cellsinfected with HIV.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 outlines the synthesis of preferred compounds of the inventionfrom starting material 1a. The structural formulas and some of theproperties of compounds 7a-18a are summarized on Table I, below.

                  TABLE I                                                         ______________________________________                                        A. 2', 3'-Dideoxy-6-Substituted-Purines of Formula I, Z═H.                Compound                                                                      No.     X       Y      M.P. (°C.)                                                                      Rf     Yield (%)                              ______________________________________                                         7a     Cl      CH     108-110  .sup. 0.35.sup.a                                                                     82                                      8a     OH      CH     248-250 (dec)                                                                          .sup. 0.24.sup.b                                                                     45                                      9a     NH.sub.2                                                                              CH     198-200  .sup. 0.33.sup.b                                                                     81                                     10a     SH      CH     263-265 (dec)                                                                          .sup. 0.44.sup.b                                                                     73                                     11a     OH      N      180-182  .sup. 0.38.sup.b                                                                     49                                     12a     NH.sub.2                                                                              N      220-222 (dec)                                                                          .sup. 0.45.sup.b                                                                     69                                     ______________________________________                                        B. 2', 3'-Dideoxy-2,6-Disubstituted-Purines of Formula I,                     Z═NH.sub.2.                                                               Compound                                                                      No.     X       Y      M.P. (°C.)                                                                      Rf.sup.b                                                                             Yield (%)                              ______________________________________                                        13a     Cl      CH     145-147  0.64   80                                     14a     OH      CH     254-256 (dec)                                                                          0.27   61                                     15a     NH.sub.2                                                                              CH     152-155  0.41   80                                     16a     Cl      N      153-155 (dec)                                                                          0.69   81                                     17a     OH      N      223-225 (dec)                                                                          0.40   89                                     18a     NH.sub.2                                                                              N      240-242 (dec)                                                                          0.52   83                                     ______________________________________                                          .sup.a CHCl.sub.3 :MeOH, 10:1.                                               .sup.b CHCl.sub.3 :MeOH, 5:1.                                            

These compounds are candidates for clinical trials in human patientsinfected with HIV and/or afflicted with AIDS or AIDS-related complex(ARC).

The synthesis of the hydroxymethylcyclopentenyl compounds of formula7a-18a, from the versatile precursor,1α-acetylamino-4α-acetoxymethylcyclopent-2-ene (1a) was accomplished asoutlined in FIG. 1. Compound 1a was prepared as described in U.S. Pat.No. 4,138,562, the disclosure of which is incorporated by referenceherein. Compound 2a was prepared from compound la by hydrolysis in thepresence of a mild base, such as an alkaline earth metal hydroxide. Toafford the pyrimidine compound 3a, Z═H, compound 2a was reacted with anexcess of 5-amino-4,6-dichloropyrimidine in the presence of an aminebase, such as a trialkylamine, in an alcoholic solvent. Also,2-amino-4,6-dichloropyrimidine was reacted with compound 2a to yieldcompound 4a.

Para-chloroaniline was diazotized with acidic sodium nitrite and reactedwith compound 4a to yield the chlorophenylazo intermediate 5a. Reductionof the azo intermediate 5a to yield 6a was accomplished with zinc andacetic acid. See Shealy and Clayton, J. Pharm. Sci., 62, 1433 (1973).

The 5-amino-6-chloro-4-pyrimidinyl intermediate 3a was converted to the9-substituted-6-chloropurine 7a (Z═H) by ring closure withtriethylorthoformate and subsequent mild acid hydrolysis to removeethoxymethylidenes and formates formed during the reaction. In likemanner, the 2,5-diamino-6-chloro-4-pyrimidinyl intermediate 6a wasring-closed to the corresponding 2-amino-6-chloro-9H-purin-9-yl compound13a.

The 6-chloropurines 7a and 13a were converted to the corresponding6-hydroxy purines 8a and 14a, respectively, with aqueous base, i.e., byrefluxing them with an alkali metal hydroxide such as NaOH. Chlorocompounds 7a, 13a and 16a were converted to the corresponding aminocompounds 9a, 15a and 18a by reaction with liquid ammonia underpressure.

Mono- or di-substituted 6-amino compounds of formula I, wherein X is NR₂and R═R═(lower)alkyl, phenyl or mixtures thereof with H, can be preparedby conventional methods for the conversion of halides to secondary ortertiary amines. For example, see I. T. Harrison et al., Compendium ofOrganic Synthetic Methods, Wiley-Interscience, NY (1971) at pages250-252. The 6-chloro substituent in compounds 7a, 13a and 16a can bereplaced with other halogen atoms by the use of various p-(halo)benzenediazonium chlorides in the conversion of 4a to 5a, or by conventionalmethods of halide-halide exchange.

These conversions are extensively described in the context of purinenucleoside synthesis in Nucleoside Analogs-Chemistry, Biology andMedical Applications, R. T. Walker et al., eds., Plenum Press, NY (1979)at pages 193-223, the disclosure of which is incorporated by referenceherein.

Treatment of 7a with thiourea in refluxing alcohol, followed by alkalinehydrolysis afforded thiol 10a. See L. F. Fieser et al., Reagents forOrganic Synthesis, John Wiley and Sons, Inc., NY (1967) at pages1165-1167 and U.S. Pat. No. 4,383,114, the disclosures of which areincorporated by reference herein. Phenyl or alkylthio-derivatives can beprepared from the corresponding thiols by the procedure of U.S. Pat. No.4,383,114 (Example 6).

Ring closure of 3a with acidic aqueous sodium nitrate followed byneutralization with aqueous base directly afforded the corresponding7-hydroxy-3H-1,2,3-triazolo[4,5d]pyrimidin-3-yl compound 11a. Ringclosure of 6a afforded the corresponding5-amino-7-chloro-3H-1,2,3-triazo[4,5d]pyrimidin-3-yl compound 16a, whichwas hydrolyzed to the corresponding 7-hydroxy compound 17a with aqueousNaOH. Compound 3a was converted to the corresponding 7-amino compounds12a by reaction with acidic sodium nitrite, followed by reaction of thecrude product with liquid ammonia. Compounds of formula I, wherein Z isOH, X is NH₂ or OH, and Y is CH can be prepared from compounds 14a, 15aby deamination of the 2-amino group with nitrous acid, employing theprocedure used by Davoll to convert 2-aminoadenosine to isoguanosine.See J. Davoll, J. Amer. Chem. Soc., 73, 3174 (1951), the disclosure ofwhich is incorporated by reference herein.

Compounds of formula I, wherein X is H, Z is NH₂ and Y is CH can beprepared from compounds 7a or 13a by dehalogenation with zinc/water [J.R. Marshall et al., J. Chem. Soc., 1004 (1951)] or by photolysis in drynitrogen-purged tetrahydrofuran containing 10% triethylamine in aRayonet photochemical reactor (2537 Å) by the method of V. Nair et al.,J. Org. Chem., 52, 1344 (1987).

Phosphate or alkanoyl esters of compounds of formula I can be preparedas disclosed in R. Vince (U.S. Pat. No. 4,383,114), the disclosure ofwhich is incorporated by reference herein, employing selectiveprotection of, e.g., the hydroxymethyl or 6-hydroxyl groups, asnecessary. Pharmaceutically-acceptable acid salts of compounds 7a-18acan be prepared as described in U.S. Pat. No. 4,383,114, the disclosureof which is incorporated by reference herein.

The invention will be further described by reference to the followingdetailed examples wherein elemental analyses were performed by M-H-WLaboratories, Phoenix, AZ. Melting points were determined on a Mel-Tempapparatus and are corrected. Nuclear magnetic resonance spectra wereobtained on Jeol FX 90QFT or Nicollet NT300 spectrometers and wererecorded in DMSO-D₆. Chemical shifts are expressed ppm downfield fromMe₄ Si. IR spectra were determined as KBr pellets with a Nicollet 50XCFT-IR spectrometer, and UV spectra were determined on a Beckmann DU-8spectrophotometer. Mass spectra were obtained with an AEI ScientificApparatus Limited MS-30 mass spectrometer. Thin layer chromatography(TLC) was performed on 0.25 mm layers of Merck silica gel 60F-254 andcolumn chromatography on Merck 60 silica gel (230-400 mesh). Allchemicals and solvents are reagent grade unless otherwise specified.

EXAMPLE 1(±)-(1α,4α)-4-[(5-Amino-6-chloro-4-pyrimidinyl)-amino]-2-cyclopentenylcarbinol(3a)

A mixture of 1a (3.0 g, 15 mmol) and aqueous barium hydroxide (0.5N, 300ml) was refluxed overnight. After cooling, it was neutralized with dryice. The precipitate was filtered out, and the aqueous solution wasconcentrated to dryness. The residue was extracted with absolute ethanoland concentrated again to yield 2a as a colorless syrup 1.6 g (14 mmol).

To this syrup, 5-amino-4,6-dichloropyrimidine (4.59 g, 28 mmol),triethylamine (4.2 g, 42 mmol), and n-butanol (50 ml) were added and themixture was refluxed for 24 hr. The volatile solvents were removed, theresidue was absorbed on silica gel (7 g), packed in a flash column(4.0×12 cm) and eluted with CHCl₃ -MeOH (20:1) to yield 2.69 g (74%) ofcompound 3a; mp 130°-132° C. An analytical sample was obtained byrecrystalization from ethyl acetate (EtOAc), mp 134°-135° C., MS (30 ev,200° C.); m/e 240 and 242 (M⁺ and M⁺ +2), 209 (M⁺ -31), 144 (B⁺); IR:3600-2600 (OH), 1620,1580 (C═C, C═N); Anal. (C₁₀ H₁₃ ClN₄ O) C,H,N.

EXAMPLE 2 (±)-(1α,4α)-4-[(2-Amino-6-chloro-4-pyrimidinyl)-amino]-2-cyclopentenylcarbinol (4a)

To 14 mmol of crude 2a, 2-amino-4,6-dichloropyrimidine (3.74 g, 22.8mmol), triethylamine (15 ml) and n-butanol (75 ml) were added and themixture was refluxed for 48 hr. The volatile solvents were removed,residue was treated with methanol to separate the undissolved byproduct(the double pyrimidine nucleoside). The methanol solution was absorbedon silica gel (8 g) packed into a column (4.0 ×14 cm) and eluted withCHCl₃ -MeOH (40:1) to yield 1.52 g (42%) of crude 4a. The product wasrecrystalized from ethyl acetate to yield 4a; mp 132°-134° C., MS (30ev, 200° C.); m/e 240 and 242 (M⁺ and M⁺ +2), 209 (M⁺ -31), 144 (B⁺);IR: 3600-3000 (NH₂, OH), 1620,1580 (C═C, C═N); Anal. (C₁₀ H₁₃ ClN₄ O)C,H,N.

EXAMPLE 3(±)-(1α,4α)-4-{[2-Amino-6-chloro-5-(4-chlorophenyl)-azo]-4-pyrimidinyl]-amino}-2-cyclopentenylcarbinol (5a)

A cold diazonium salt solution was prepared from p-chloroaniline (1.47g, 11.5 mmol) in 3N HCl (25 ml) and sodium nitrite (870 mg, 12.5 mmol)in water (10 ml). This solution was added to a mixture of 4a (2.40 g, 10mmol), acetic acid (50 ml), water (50 ml) and sodium acetate trihydrate(20 g). The reaction mixture was stirred overnight at room temperature.The yellow precipitate was filtered and washed with cold water untilneutral, then it was air-dried in the fumehood to yield 3.60 g (94%), of5a, mp 229° C. (dec). The analytical sample was obtained fromacetone-methanol (1:2), mp 241°-243° C. (dec). MS (30 ev, 260° C.): m/e378 and 380 (M⁺ and M⁺ +2), 282 (B⁺); IR: 3600-3000 (NH₂, OH), 1620,1580(C═C, C═ N); Anal. (C₁₆ H₁₆ Cl₂ N₆ O) C,H,N.

EXAMPLE 4 (±)-(1α,4α)-4-(2,5-Diamino-6-chloro-4-pyrimidinylamino]-2cyclopentenYlcarbinol (6a).

A mixture of 5a (379 mg, 1 mmol), zinc dust (0.65 g, 10 mmol), aceticacid (0.32 ml), water (15 ml) and ethanol (15 ml) was refluxed undernitrogen for 3 hr. The zinc was removed and the solvents wereevaporated. The residue was absorbed on silica gel (2 g), packed into acolumn (2.0×18 cm), and eluted with CHCl₃ --MeOH (15:1). A pink syrupwas obtained. Further purification from methanol-ether yielded 6a aspink crystals, 170 mg (66%), mp 168°-170° C., MS (30 ev, 220° C.); m/e255 and 257 (M⁺ and M⁺ +2), 224 (M⁺ -31), 159 (B⁺); IR: 3600-3000 (NH₂,OH), 1620,1580 (C═C, C═N); Anal. (C₁₀ H₁₄ ClN₅ O) C,H,N.

EXAMPLE 5 (±)-(1α,4α)-4-(6-chloro-9H-purin-9-yl)-2-cyclopentenylcarbinol(7a)

A mixture of 3a (1.30 g, 5.4 mmol), triethyl orthoformate (30 ml) andhydrochloric acid (12N, 0.50 ml) was stirred overnight at roomtemperature. The solvent was evaporated at 35° C. in vacuo. To theresidue was added aqueous hydrochloric acid (0.5N, 30 ml) and themixture was stirred for 1 hr. The mixture was neutralized to pH 7-8 with1N sodium hydroxide and absorbed onto silica gel (8 g), packed in acolumn (4.0×8 cm), and eluted with CHCl₃ --MeOH (20:1) to yield whitecrystals of 7a, 1.12 g (82%). The crude product was recrystalized fromethyl acetate to yield 7a, mp 108°-110° C., MS (30 ev, 200° C.); m/e 250and 252 (M⁺ and M⁺ +2), 219 (M⁺ -31), 154 (B⁺); IR: 3600-2800 (OH), 1600(C═C, C═N); Anal. (C₁₁ H₁₁ ClN₄ O) C,H,N.

EXAMPLE 6(±)-(1α,4α)-4-(6-Hydroxy-9H-purin-9-yl)-2-cyclopentenylcarbinol (8a)

A mixture of 7a (251 mg, 1 mmol) and aqueous sodium hydroxide (0.2N, 10ml) was refluxed for 3 hr. After cooling, the reaction mixture wasadjusted to pH 5-6 with acetic acid. The reaction mixture was absorbedon silica gel (2 g) packed in a column (2.0×11 cm) and eluted with CHCl₃-MeOH (10:1) to yield 105 mg (45%) of 8a. The crude white product wasrecrystalized from water-methanol (3:1) to yield 8a, mp 248°-250° C.(dec), MS (30 ev, 300° C.); m/e 232 (M⁺), 214 (M⁺ -18), 136 (B⁺); IR;3600-2600 (OH), 1680,1600 (C═O, C═C, C═N); Anal. (C₁₁ H₁₂ N₄ O₂) C,H,N.

EXAMPLE 7 (±)-(1α,4α-4-(6-Amino-9H-purin-9-yl)-2-cyclopentenylcarbinol(9a)

Liquid ammonia was passed into a bomb containing a solution of 7a (250mg, 1 mmol) in methanol (5 ml) at -80° C. The bomb was sealed and heatedat 60° C. for 24 hr. Ammonia and methanol were evaporated and theresidue was recrystalized from water to yield off-white crystals of 9a,187 mg (81%), mp 198°-200° C., MS (30 ev, 210° C.): m/e 231 (M⁺), 213(M⁺ -18), 135 (B⁺); IR: 3600-2600 (NH₂, OH), 1700,1600 (C═C, C═N); Anal.(C₁₁ H₁₃ N₅ O) C,H,N.

EXAMPLE 8(±)-(1α,4α)-4-(6-Mercapto-9H-purin-9-yl)-2-cyclopentenylcarbinol (10a)

A mixture of 7a (125 mg, 0.5 mmol), thiourea (40 mg, 0.64 mmol) andn-propanol (5 ml was refluxed for 2 hr. After cooling, the precipitatewas isolated by filtration, washed with n-propanol, and dissolved insodium hydroxide (1N, 5 ml). The solution was adjusted to pH 5 withacetic acid. The crude 10a (90 mg, 73%) was isolated again, mp 260°-262°C. (dec) and was recrystalized from N,N-dimethylformamide, to yield 10a,mp 263°-265° C. (dec) MS (30 ev, 290° C.): m/e 248 (M⁺), 230 (M⁺ -18),152 (B⁺); IR: 3600-3200 (OH), 3100,2400 (SH), 1600 (C═C, C═N); Anal.(C₁₁ H₁₂ N₄ OS) C,H,N.

EXAMPLE 9(±)-(1α,4α)-4-(7-Hydroxy-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl)-2-cyclopentenyl carbinol (11a).

To a cold solution of 3a (361 mg, 1.5 mmol) in hydrochloric acid (1N, 30ml) was added sodium nitrite solution (120 mg, 1.7 mmol) in 3 ml ofwater. The reaction was monitored by starch-potassium iodide paper. Themixture concentrated at 40° C. to a volume of 2 ml and adjusted to pH 7with aqueous sodium hydroxide. The mixture was absorbed on silica gel (2g), packed in a column (2.0×13 cm) and eluted with CHCl₃ -MeOH (10:1).The crude 11a was recrystallized from water-methanol (3:1) to yieldwhite crystals of 11a, 173 mg (49%) mp 180°-182° C. MS (30 ev, 230° C.):m/e 233 (M⁺), 203 (M⁺ -30), 137 (B⁺); IR: 3600-2600 (OH), 1740,1600(C═O, C═C, C═N); Anal. (C₁₀ H₁₁ N₅ O₂) C,H,N.

EXAMPLE 10(±)-1α,4α)-4-(7-Amino-3H-1,2,3-triazolo[4,5d]pyrimidin-3-yl)-2-cyclopentenylcarbinol (12a)

Sodium nitrite solution (828 mg, 12 mmol) in water (10 ml) was addeddropwise to a cold solution of 3a (2.43 g, 10.1 mmol) in hydrochloricacid (0.5N, 40 ml). The reaction mixture was stirred at room temperaturefor 1 hr, then concentrated to a syrup. The syrup was dissolved inethanol and transferred into a stainless steel bomb. Liquid ammonia waspassed in, the bomb was sealed, and the reaction mixture was stirred atroom temperature overnight. Ammonia was evaporated and the residue waschromatographed on silica gel (150 g) eluting with CH₂ Cl₂ --MeOH (10:1)to yield white crystals of 12a, 1.62 g (69%), mp 220°-222° C. (dec). MS(30 ev, 220° C.): m/e 232 (M⁺), 202 (M⁺ -30), 136 (B⁺); IR: 3600-2800(NH₂, OH), 1700,1600 (C═C, C═N); Anal. (C₁₀ H₁₂ N₆ O) C,H,N.

EXAMPLE 11(±)-(1α,4α)-4-(2-Amino-6-chloro-9H-purin-9-yl)-2-cyclopentenyl carbinol(13a)

A mixture of 6a (1.41 g, 5.5 mmol) triethyl orthoformate (30 ml) andhydrochloric acid (12N, 1.40 ml) was stirred overnight. The suspensionwas dried in vacuo. Diluted hydrochloric acid (0.5N, 40 ml) was addedand the mixture was reacted at room temperature for 1 hr. The mixturewas neutralized to pH 8 with 1N sodium hydroxide and absorbed on silicagel (7.5 g) packed in a column (4.0×10 cm) and eluted by CHCl₃ -MeOH(20:1) to yield off-white crystals of 13a, 1.18 g (80%). The crudeproduct was recrystalized from ethanol to yield 13a, mp 145°-147° C. MS(30 ev, 220° C.): m/e 265 and 267 (M⁺ and M⁺ +2), 235 (M⁺ -30), 169(B⁺); IR: 3600-2600 (NH₂, OH), 1620,1580 (C═C, C═N); Anal. (C₁₁ H₁₂ N₅OCl^(a) 3/4 H₂ O) C,H,N.

EXAMPLE 12 (±)-(1α,4α)-4-(2-Amino-6-hydroxy-9H-purin-9-yl)-2-cyclopentenyl carbinol (14a)

A mixture of 13a (266 mg, 1 mmol) and aqueous sodium hydroxide (0.33N)was refluxed for 5 hr., absorbed onto silica gel (2 g) packed in acolumn (2.0×7.5 cm) and eluted with CHCl₃ --MeOH (5:1). The crudeproduct was recrystalized from methanol-water (1:4) to yield whitecrystals of 14a, 152 mg (61%), mp 254°-256° C. (dec). MS (30 ev, 200°C.): m/e 247 (M⁺), 217 (M⁺ -30), 151 (B⁺); IR: 3600-2600 (NH₂, OH),1700,1600 (C═O, C═C, C═N); Anal. (C₁₁ H₁₃ N₅ O₂ ^(a) 3/4 H₂ O) C,H,N.

EXAMPLE 13(±)-(1α,4α)-4-(2,6-Diamino-9H-purin-9-yl)-2-cyclopentenylcarbinol (15a)

Liquid ammonia was passed into a solution of 13a (265 mg, 1 mmol) inmethanol (10 ml) at -80° C. in a bomb. The bomb was sealed and heated at75° C. for 48 hr. Ammonia and methanol were evaporated. The residue wasabsorbed on silica gel (2 g), packed in a column (2.0×10 cm) and elutedwith CHCl₃ -MeOH (15:1). The crude product was recrystalized fromethanol to yield 196 mg (80%) of 15a, mp 152°-155° C. MS (30 ev, 200°C.): m/e 246 (M⁺), 229 (M⁺ -17), 216 (M⁺ -30), 150 (B⁺); IR: 3600-3000(NH₂, OH), 1700,1650,-1600 (C═O, C═C, C═N); Anal. (C₁₁ H₁₄ N₆ O) C,H,N.

EXAMPLE 14(±)-(1α,4α)-4-(5-Amino-7-chloro-3H-1,2,3-triazolo[4,5d]pyrimidin-3-yl)-2-cyclopentenyl carbinol (16a)

To a cold solution of 6a (225 mg, 1 mmol) in acetic acid (1.5 ml) andwater (2.5 ml) was added sodium nitrite (83 mg, 1.2 mmol) in water (2ml). The reaction was monitored by starch-potassium iodide paper. Afterstirring for 1 hr. at 0° C., the precipitate was filtered and washedwith cold water, then dried over phosphorus pentoxide in vacuo to yield16a as off-white crystals, 218 mg (81%). The crude 16a was recrystalizedfrom methanol, mp 153°-155° C. (dec). MS (30 ev, 220° C.): m/e 266 and268 (M⁺ and M⁺ +2), 236 (M⁺ -30), 170 (B⁺); IR: 3600-3000 (NH₂, OH),1650,1600 (C═C, C═N); Anal. (C₁₀ H₁₁ ClN₆ O) C,H,N.

EXAMPLE 15 (±)-(1α,4α)-4-(5-Amino-7-hydroxy-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl)-2-cyclopentenyl carbinol (17a)

A mixture of 16a (218 mg, 0.8 mmol) and aqueous sodium hydroxide (0.25N,10 ml) was refluxed for 3 hr, then was adjusted to pH 3 with 6 Nhydrochloric acid. The gelatinious precipitate was filtered and washedwith cold water. It was dried over phosphorous pentoxide in vacuo toyield 17a as an off-white solid, 181 mg (90%) mp 222°-224° C. (dec)After recrystalization from water, the mp was 223°-225° C. (dec). MS (20ev, 300° C.): m/e 248 (M⁺), 217 (M⁺ -31), 152 (B⁺); IR: 3600-3000 (NH₂,OH), 1750,1600 (C═C, C═N); Anal. (C₁₀ H₁₂ N₆ O₂.1/2 H₂ O) C,H,N.

EXAMPLE 16(±)-(1α,4α)-4-(5,7-Diamino-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl)-2-cyclopentenylcarbinol (18a)

Compound 16a (267 mg, 1 mmol) was processed as described in Example 13,employing a reaction time of 60° C. for 20 hr. The residual mixture wasabsorbed on silica gel (2 g), packed in a column (2.0×10 cm) and elutedby CHCl₃ -MeOH (15:1) to yield 18a as white crystals, 204 mg (83%). Thecrude product was recrystalized from ethanol-water (2:1), to yield 18aof mp 240°-242° C. (dec). MS (30 ev, 240° C.): m/e 247 (M⁺), 229 (M⁺-18), 217 (M+-30), 151 (B⁺); IR: 3600-3100 (NH₂, OH), 1700,1650,1600(C═O, C═C, C═N); Anal. (C₁₀ H₁₃ N₇ O. H₂ O) C,H,N.

EXAMPLE 17(±)-(1α,4α)-4-(3-Methoxy-2-methylacryloylureido)-2-cyclopentenylcarbinol (19a)

Isocyanate reagent was prepared from 3-methoxy-2-methylacryloyl chloride(1.00 g, bp 65°-66° C./2.5 mm) in anhydrous benzene (10 ml) and freshlydried silver cyanate (2.6 g, 17 mmol, dried at 110° C., 2 hrs) byrefluxing for 0.5 hr. The supernatant was added dropwise into a solutionof 2a (from 1a, 0.8 g, 4 mmol) in N,N-dimethylformamide (10 ml) at -15°C. and the mixture was stirred for 1 hr, then stored at 4° C. overnight.The solvent was evaporated and the residue was absorbed on silica gel (3g), packed in a column (2.0×16 cm) and eluted with CHCl₃ --MeOH (20:1)to yield white crystals of 19a, 605 mg, (60%), mp 147°-149° C. MS (30ev, 200° C.): m/e 254 (M⁺), 239 (M⁺ -15), 223 (M⁺ -31), 158 (B⁺); IR:3600-2800 (NH₂, OH), 1700,1650,1600 (C═O, C═C); Anal. (C₁₂ H₁₈ N₂ O₄)C,H,N.

EXAMPLE 18(±)-(1α,4α)-4-5-Methyl-2,4-(1H,3H)-pyrimidinedion-3-yl]-2-cyclopentenylcarbinol (20a)

A mixture of 19a (381 mg, 1.5 mmol), p-toluenesulfonic acid monohydrate(20 mg) and anhydrous N,N-dimethylformamide (2 ml) was stirred at 115°C. for 3 hr. The solvent was evaporated, the residue was absorbed onsilica gel (3 g), packed in a column (2.0×14 cm) and eluted with CHCl₃--MeOH (20:1) to yield 20a as off-white crystals, 206 mg (62%) Theproduct was recrystalized from absolute ethanol to yield 20a, mp213°-215° C. MS (30 ev, 250° C.): m/e 222 (M⁺), 204 (M⁺ -18), 191 (M⁺-31), 126 (B⁺); IR: 3600-3300 l (OH), 1700,1600 (C═O, C═C); Anal. (C₁₁H₁₄ N₂ O₃) C,H,N.

EXAMPLE 19 Esterification of Compound 14a (1α,4α)-4-(2-Amino-6-hydroxy-9H-purin-9-yl)-2-cyclopentenyl Acetoxycarbinol

To a suspension of 14a (130 mg, 0.50 mmol) and 4-dimethylaminopyridine(5 mg, 0.04 mmol) in a mixture of acetonitrile (6 ml) and triethylamine(0.09 ml, 0.66 mmol) was added acetic anhydride (0.06 ml, 0.6 mmole).The mixture was stirred at room temperature for 3 hr. Methanol (1 ml)was added to quench the reaction. The solution was concentrated andabsorbed on silica gel (1.5 g), packed on a column (2.0×12 cm), andeluted with CHCl₃ --MeOH (20:1). The product fractions were collectedand concentrated to yield a white solid. The solid product was washedwith MeOH--AcOEt to yield 123 mg of the purified acetoxycarbinol (85%).Further purification from methanol afforded needle-like crystals, mp237°-239° C.; Anal. (C₁₃ H₁₅ N₅ O₃) C,H,N.

EXAMPLE 20 (1S,4R)-4-(2-Amino-6-hydroxy-9H-Purin-9-yl)-2-cyclopentenylCarbinol ((-)14a).

The diamino analog, 15a, (100 mg) was dissolved in 3 ml of 0.05M K₂ PO₄buffer (pH 7.4) at 50° C. The solution was cooled at 25° C. and 40 unitsof adenosine deaminase (Sigma, Type VI, calf intestinal mucosa) wasadded. After three days of incubation at room temperature, a precipitateformed and was removed by filtration to yield 18.2 mg of crude product.The filtrate was concentrated to 1.5 ml and refrigerated for 2 days.Additional solid (26.8 mg) was obtained by filtration. The two solidfractions were recrystalized from water to yield the pure product, mp269°-272° C.;[α]_(D) ²⁴ -62.1 (c 0.3 MeOH).

EXAMPLE 21 (1R,4S)-4-(2-Amino-6-hydroxy-9H-purin-9-yl)-2-cyclopentenylcarbinol ((+)14a).

The filtrates from the preparation of the 1S,4R isomer were combined andevaporated to dryness. The unchanged diamino starting material wasseparated on a silica gel flash column using 10% methanol/chloroform.The diamino compound was dissolved in 0.05M K₂ PO₄ buffer, pH 7.4 (15ml) and 800 units of adenosine deaminase was added. The solution wasincubated for 96 hr at 37° C. TLC indicated some unreacted productremained. The solution was heated in boiling water for 3 min andfiltered to remove denatured protein. Another 800 units of adenosinedeaminase was added and the processes were repeated. The deproteinatedsolution was evaporated to dryness and the product was crystalized fromwater to yield a white solid; mp 265°-270° C.;[α]_(D) ²⁴ +61.1 (c 0.3MeOH).

EXAMPLE 22 Cytotoxicity Assay

The ED₅₀ cytotoxicity concentrations determined for analogs 7a, 9a, 10a,16a, and in the P-388 mouse leukemia cell culture assay are given inTable II.

                  TABLE II                                                        ______________________________________                                        Inhibitory Concentrations of Carbocyclic Nucleosides for P-388                Leukemia Cells in Cultures*                                                   Compound      ED.sub.50, μg/ml                                             ______________________________________                                         7a           12.0                                                             9a           40.0                                                            10a           3.0                                                             16a           1.0                                                             17a           4.5                                                             ______________________________________                                         *Assay Technique: R. G. Almquist and R. Vince, J. Med. Chem., 16, 1396        (1973).                                                                  

Therefore, all of the compounds listed on Table II are active againstP-388 mouse leukemia.

EXAMPLE 23 Anti-HIV Assay

Compounds of formula I were screened for anti-HIV activity at theNational Cancer Institute, Frederick Cancer Research Facility,Frederick, Maryland (FCRF). The following are the current screening modeoperational procedures utilized at FCRF. The protocol consists of 3areas, (I) preparation of infected cells and distribution to the testplates, (II) preparation of drug dilution plates and distribution to thetest plates, and (III) XTT assay procedure. See D. A. Scudiero et al.,"A New Simplified Tetrazolium Assay for Cell Growth and Drug Sensitivityin Culture," Cancer Res., 48, 4827 (1988).

I. Infection and Distribution of Cells to Microtiter Trays

Cells to be infected (a normal lymphoblastoid cell line which expressesCD4) are placed in 50 ml conical centrifuge tubes and treated for 1 hrwith 1-2 μg/ml of polybrene at 37° C. The cells are then pelleted for 8min. at 1200 rpm. HIV virus, diluted 1:10 in media (RMPl-1640, 10% humanserum or 15% fetal calf serum (FCS), with IL-2, for ATH8 cells only, andantibiotics) is added to provided an MOI of 0.001. Medium alone is addedto virus-free control cells. Assuming an infectious virus titer of 10⁻⁴,an MOI of 0.001 represents 8 infectious virus particles per 10,000cells. About 500,000 cells/tube are exposed to 400 μl of the virusdilution. The resultant mixture is incubated for 1 hr at 37° C. inAir-CO₂. The infected or uninfected cells are diluted to give 1×10⁻⁴(with human serum or 2×10⁻⁴ with calf serum) cells/100 μl.

Infected or uninfected cells (100 μl) are distributed to appropriatewells of a 96 well, U-bottom, microtiter plate. Each compound dilutionis tested in duplicate with infected cells. Uninfected cells areexamined for drug sensitivity in a single well for each dilution ofcompound. Drug-free control cells, infected and uninfected, are run intriplicate. Wells B2 through G2 served as reagent controls and receivedmedium only. The plates are incubated at 37° C. in Air-CO₂ until thedrug is added.

II. Drug Dilution and Addition

Dilution plates (flat bottom 96 well, microtiter plates) are treatedovernight with phosphate buffered saline (PBS) or media containing atleast 1% FCS or 1% human serum (depending on the medium used in thetest), beginning the day before assay. This "blocking" procedure is usedto limit the adsorption of drug to the microtiter tray during thedilution process. The wells are filled completely with the blockingsolution and allowed to stand at room temperature in a humidifiedchamber in a hood.

The dilution process is begun by first diluting the test compound 1:20.Blocked, dilution plates are prepared by flicking out the blockingsolution and blotting dry on sterile gauze. All wells of each plate arethen filled with 225 μl of the appropriate medium using a Cetus liquidhandling system. Twenty-five microliters (25 μl) of each 1:20 dilutedcompound is then manually added to row A of a blocked and filleddilution plate. Four compounds, sufficient to supply two test plates,are added per dilution plate. The four compounds are then seriallydiluted ten-fold from row A through row H using the Cetus liquidhandling system. The starting dilution of each compound in row A is, atthis point, 1:200. The dilution plates are kept on ice until needed.

Using a multi-channel pipettor with 6 microtips, 100 μl of each drugdilution is transferred to the test plate which already contains 100 μlof medium plus cells. The final dilution, in the test plate, starts at1:400 (wells B4 through G4). This dilution (to 0.25% DMSO) prevents theDMSO vehicle from interfering with cell growth. Drug-free, infected oruninfected cells (wells B3 through G3) and reagent controls (B2 throughG2) receive medium alone. The final two compounds are then transferredfrom wells H7 through H12 to a second test plate using the sameprocedure. Test plates are incubated at 37° C. in Air-CO₂ for 7-14 daysor until virus controls are lysed as determined macroscopically.

III. Quantitation of Viral Cytopathogenicity and Drug Activity A.Materials

1. A solution of2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide. (XTT)--1 mg./ml solution in mediawithout FCS. Store at 4° C. Prepare weekly.

2. Phenazine methosulfonate (PMS) stock solution--This can be preparedand maintained frozen until needed at -20° C. It should be made in PBSto a concentration of 15.3 mg/ml.

B. Microculture Tetrazolium Assay (MTA)

1. Preparation of XTT-PMS Solution--The XTT-PMS is prepared immediatelyprior to its addition to the wells of the culture dish. The stock PMSsolution is diluted 1:100 (0.153 mg/ml). Diluted PMS is added to everyml of XTT required to give a final PMS concentration of 0.02 mM. A 50 μlaliquot of the XTT-PMS mixture is added to each of the appropriatewells, and the plate is incubated for four hours at 37° C. The platelids are removed and replaced with adhesive plate sealers (Dynatech cat001-010-3501). The sealed plate is shaken on a microculture plate mixerand the absorbance is determined at 450 nm.

IV. Results

FIG. 2 depicts a plot of the percentage of test cells over uninfectedcells (%) for both infected and uninfected cells as a function of theincreasing concentration of compound 14a.

The data plotted on FIG. 2 permit the calculation of an effectiveconcentration (EC₅₀) with respect to infected cells of about 0.15 μg/ml,an inhibitory concentration (IC₅₀) with respect to normal cells of about100 μg/ml, and a therapeutic index (TI₅₀) of about 667. An earlier assaycarried out at the Southern Research Institute yielded a TI₅₀ of about200 when MT-2 cells were cultured with H9/HTLV-IIIB.

The HIV inhibitory concentrations of compounds 7a, 9a, 10a, 13a, 14a,and 15a are given on Table III, below.

                  TABLE III                                                       ______________________________________                                        HIV Inhibitory Concentrations.sup.a                                           Compound      ED.sub.50 (μg/ml)                                            ______________________________________                                         7a           >10                                                              9a           2.3                                                             10a           >10                                                             13a           0.41                                                            14a           0.15                                                            15a           2.9                                                             (-)14a.sup.   0.66                                                            ______________________________________                                         .sup.a MT2 host cells, except ()14a, which was assayed in CEM cells,          exhibiting an IC.sub.50 of 189.                                          

Compound 14a was also found to be active against feline leukemia virus(ED₅₀ =1.9; FAIDS variant); murine leukemia virus (ED₅₀ =1.1; Cas-BR-Mtype) and simian AIDS virus (ED₅₀ =2.8; D/Washington type).

The invention comprises the biologically active compounds as disclosedor the pharmaceutically acceptable salts or esters thereof, togetherwith a pharmaceutically acceptable carrier for administration ineffective non-toxic dose form. Pharmaceutically acceptable salts may besalts of organic acids, such as acetic, lactic, malic or p-toluenesulphonic acid and the like as well as salts ofpharmaceutically-acceptable mineral acids, such as hydrochloric orsulfuric acid and the like. Other salts may be prepared and thenconverted by conventional double decomposition methods intopharmaceutically-acceptable salts directly suitable for purposes oftreatment of viral infections in mammals or for the prevention of viralcontamination of physiological fluids such as blood or semen in vitro.

Pharmaceutically acceptable carriers are materials useful for thepurpose of administering the present analogs and may be solid, liquid orgaseous materials, which are otherwise inert and medically acceptableand are compatible with the active ingredients. Thus, the present activecompounds can be combined with the carrier and added to physiologicalfluids in vitro or administered in vivo parenterally, orally, used as asuppository or pessary, applied topically as an ointment, cream,aerosol, powder, or given as eye or nose drops, etc., depending uponwhether the preparation is used for treatment of internal or externalviral infections.

For internal viral infections, the compositions may be administeredorally or parenterally at effective non-toxic antivirus dose levels ofabout 10 to 750 mg/kg/day of body weight given in one dose or severalsmaller doses throughout the day. For oral administration, fine powdersor granules may contain diluting, dispersing and/or surface activeagents and may be presented in water or in a syrup; in capsules in thedry state, or in a non-aqueous solution or suspension; in tablets or thelike. Where desirable or necessary, flavoring, preserving, suspending,thickening, or emulsifying agents may be included. For parenteraladministration, administration as drops, the compounds may be presentedin aqueous solution in an effective, non-toxic dose in concentration offrom about 0.1 to 10 percent w/v. The solutions may containantioxidants, buffers and the like. Alternatively, for infections ofexternal tissues, the compositions are preferably applied as a topicalointment or cream in concentration of about 0.1 to 10 percent w/v.

Projected Clinical Trial to Evaluate Ability of Compound 14a+AZT toInhibit the Progression of HIV Infection

AZT administration can decrease mortality and the frequency ofopportunistic infection in subjects with AIDS or AIDS-related complex.M. A. Fischl et al. New Engl. J. Med., 317, 185 (1987). Therefore, manypersons who have been diagnosed HIV-positive are presently receivingdaily doses of AZT. However, AZT is myelotoxic and its administrationover a period of 2-3 years has recently been shown to either cause, orto fail to inhibit, a high incidence of the development of non-Hodgkinslymphoma. Therefore, the present study is designed to evaluate theability of compound (-)14a to inhibit the course of HIV infection.

Patients and Methods

Sixty patients, thirty with HIV infection plus AIDS-related complex andthirty with early AIDS are selected and evaluated in accord with thecriteria provided by M. A. Fischl et al., cited above. The two groups ofthirty patients are matched into pairs. A capsule containing 100 mg ofAZT or an indistinguishable capsule containing 50 mg AZT and 50 mg of(-)14a is administered orally every 4 hours throughout the 24-hour day,for 24 weeks. All of the ARC patients complete the entire study and 20of the AIDS patients complete the study.

Results Development of AIDS in ARC Patients

Four patients in the AZT group but none in the AZT+14(a) group developopportunistic infections or Kaposi sarcoma. Of the four patients in whomAIDS develops: 1 has PCP, candida pneumonia and cerebral toxoplasmosis;2 have PCP alone and 1 has non-Hodgkins lymphoma in the breast andKaposi sarcoma in a lymph node. Three of the four patients die 8, 15 and18 months after diagnosis.

Clinical Progression of AIDS

Nine of the AIDS patients treated with AZT alone die during the studywhile there is only one death in the population treated with (-)14a plusAZT. During the treatment period, two of fifteen patients who receivethe combination regimen worsen while, of the survivors, five of sixpatients receiving AZT alone worsen. The criteria for response are thoseof M. A. Fischl et al., cited above.

Discussion

Oral (-)14a +AZT administered in a 1:1 weight ratio is superior to anequivalent amount of AZT in reducing mortality due to early AIDS and theprogression of HIV infection in both ARC and early AIDS patients, for aperiod of up to 6 months. This study also validates the in vitro modelused herein to establish the anti-HIV activity of members of this classof carbocyclic nucleosides.

The invention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

What is claimed is:
 1. A compound of the formula: ##STR9## wherein Z isH or NH₂, Z' is H or NH₂ and X is halogen.
 2. The compound of claim 1wherein X is Cl.
 3. The compound of claim 1 wherein Z is NH₂.
 4. Thecompound of claim 1 wherein Z' is H.
 5. The compound of claim 3 whereinZ' is NH₂.